JP4022609B2 - Cleaning device for rod electrode - Google Patents

Description

  The present invention relates to a cleaning apparatus for a rod-shaped electrode inserted in a flow path. More specifically, the rod-shaped electrode is cleaned by rotating an electrode surface cleaning device using the flow force of a measurement liquid and rubbing against the surface of the rod-shaped electrode. The present invention relates to a rod-shaped electrode cleaning apparatus in which an electrode is continuously cleaned during a period of use. This technique is effective for cleaning a rod-shaped electrode in an apparatus for measuring a physicochemical state such as a redox potential.

  The oxidation-reduction potential of a liquid is an important factor related to chemical reaction and movement of substances in the liquid. In order to measure the oxidation-reduction potential, an oxidation-reduction potential measuring electrode using platinum or gold is generally used. However, in order to obtain accurate redox potential measurements for liquids with low concentrations of dissolved components involved in redox reactions in liquids and low chemical buffering capacity and liquids under reducing conditions, Until the measured value of the oxidation-reduction potential measurement electrode reaches a constant value, continuous measurement over a long period of time is required. Further, when a natural sample such as ground water is measured, there is a problem that it is difficult to obtain a stable measurement value due to bubbles adhering to the surface of the redox potential measurement electrode.

  As mentioned above, one of the reasons why it takes a long time for the measured value of the oxidation-reduction potential measurement electrode to reach a constant value is that the oxidation film formed on the oxidation-reduction potential measurement electrode surface during storage or contamination during use. Inhibition of the electrochemical reaction on the surface of the oxidation-reduction potential measurement electrode due to the adhesion of etc.

  Therefore, for the oxidation-reduction potential measurement electrode, maintenance such as a method of chemically removing the film or dirt on the electrode surface by acid cleaning or periodically polishing the surface of the oxidation-reduction potential measurement electrode with an abrasive has been performed. It was. However, in these methods, since maintenance is performed in an atmospheric environment, when removing a stain or film on the oxidation-reduction potential measurement electrode when measuring a sample in a reducing environment with low chemical buffering properties as described above, cleaning is performed. From when the redox potential measuring electrode is installed to the liquid sample, the surface of the redox potential measuring electrode is exposed to an oxidative environment, and there is a problem that an accurate measurement value cannot be obtained. Also, to clean the surface of the oxidation-reduction potential measurement electrode, the oxidation-reduction potential measurement electrode must be temporarily removed from the measurement liquid, resulting in missing measurement data during maintenance, and continuous measurement values over a long period of time. There are also problems that prevent acquisition.

In order to solve such a problem, an electrode cleaning apparatus has been developed that performs cleaning using a liquid flow mainly for ion electrodes that measure dissolved component concentrations (see, for example, Patent Document 1). Here, an impeller having a rotation axis substantially orthogonal to the surface of the electrode is used, and the blade side surface is configured to contact the electrode surface. However, what has been developed is for cleaning the surface of a flat plate type electrode, and cannot be used for a rod-shaped electrode. In addition, there is a problem that the measurement cannot be performed in parallel with the cleaning because it is not intended for long-term continuous monitoring measurement.
JP 2003-164818 A

  The problem to be solved by the present invention is that the film or dirt on the surface of the rod-shaped electrode can be automatically removed without touching the atmosphere, and at the same time, the rod-shaped electrode can be prevented from being contaminated or adhered during measurement. The aim is to shorten the time required for surface stabilization and to perform measurement continuously over a long period of time by eliminating maintenance. Another problem to be solved by the present invention is to make it possible to measure an accurate redox potential in a short time.

The present invention is an apparatus for cleaning the surface of a rod-shaped electrode inserted in a flow path by using a cleaning instrument that rotates using the flow force of a measurement liquid flowing in the flow path, the rod-shaped electrode An electrode surface cleaning device that includes a boss portion having a through-hole into which the boss portion is loosely fitted, and a plurality of blades disposed around the boss portion, the electrode surface cleaning device being rotatable and vertically movable as a whole with a rod-shaped electrode as a supporting shaft. A support for holding the electrode surface cleaning device so that it does not fall off, and the electrode surface cleaning device rotates in an eccentric manner while moving up and down irregularly by the flow force of the measurement liquid, and the inner surface of the through hole is This is a rod-shaped electrode cleaning apparatus in which the surface of the rod-shaped electrode is cleaned by directly rubbing at various locations on the outer surface of the rod-shaped electrode.

  Here, it is preferable that the electrode surface cleaning device is an integrally molded product of electrically insulating plastic in which a plurality of curved structure blades are arranged at an equal angle on the outer periphery of a cylindrical boss portion. The support is, for example, a frame-like or net-like structure on the outside, and has a rod-like protrusion that can be loosely fitted into the through hole so that the rotatable electrode surface cleaning device does not fall off.

  The present invention also includes a rod-shaped electrode, a redox potential measuring unit that measures a redox potential through the rod-shaped electrode, and a measurement control unit that controls display of the measurement result. This is a redox potential measuring device incorporating the cleaning device.

  The rod-shaped electrode cleaning apparatus according to the present invention uses the flow force of the measurement liquid to freely rotate about the rod-shaped electrode as a support shaft so that the inner surface of the through hole of the electrode surface cleaning device contacts the outer surface of the rod-shaped electrode and rubs against each other. Therefore, it is possible to remove the film on the surface of the rod-shaped electrode, to prevent adhesion of dirt, etc., and the rod-shaped electrode is automatically cleaned during the measurement period. In addition, by using the rod electrode cleaning apparatus according to the present invention, the oxide film on the rod electrode surface can be removed quickly, so that the measurement value of the oxidation-reduction potential can be obtained in a short time in the measurement of a sample having a low chemical buffering property. Can be obtained. Furthermore, in the long-term continuous monitoring measurement, the maintenance of the rod-shaped electrode surface becomes unnecessary, so that the measurement data is not lost due to the maintenance, and the continuous monitoring measurement period of the oxidation-reduction potential measuring device can be greatly extended. In addition, in the measurement of a natural sample, it is possible to prevent bubbles from adhering to the electrode surface due to the presence of the electrode surface cleaning tool.

  In the present invention, in order to measure the physicochemical state of a measurement liquid, the surface of the rod-shaped electrode inserted into the flow path is continuously washed during use by using the flow force of the measurement liquid. Device. This rod-shaped electrode cleaning apparatus includes an electrode surface cleaning tool and a support for holding the electrode surface cleaning tool. The electrode surface cleaning tool includes a boss portion having a through hole in which the rod-shaped electrode is loosely fitted, and a plurality of curved structure blades radially arranged at an equal angle on the outer periphery of the boss portion, It is an integrally molded product of insulating plastic. The electrode surface cleaning device is rotatable as a whole with a rod-shaped electrode as a support shaft. On the other hand, the support is provided with a frame-like or net-like structure on the outside so that the measuring liquid can flow without resistance, and a rod-like protrusion provided on the structure, and the electrode-like surface that can be rotated freely by the rod-like protrusion It is a structure which hold | maintains so that an instrument may not fall from a rod-shaped electrode.

  In the flow of the measurement liquid, the flow force is changed to a rotational force by the blades. Due to the flow of the measurement liquid that has passed through the frame-like or net-like support, the blades obtain a rotational force, and the rotational force causes the electrode surface cleaning device to rotate about the rod-shaped electrode as a support shaft. The surface of the rod-shaped electrode is cleaned by rubbing against the outer surface of the rod-shaped electrode. At this time, if the electrode surface cleaning device and the support are made of an electrically insulating material, the redox potential measurement will not be adversely affected.

  Such a rod-shaped electrode cleaning device is typically incorporated in a redox potential measuring device or the like. The oxidation-reduction potential measuring device includes a rod-shaped electrode, an oxidation-reduction potential measuring unit that measures the oxidation-reduction potential through the rod-shaped electrode, a measurement control unit that controls display of the measurement result, and the like. In general, a standard electrode and a rod-shaped electrode are provided for the oxidation-reduction potential measurement. However, a standard electrode can be incorporated in the oxidation-reduction potential measurement unit. Such a configuration is preferable.

  The electrode surface cleaning tool is equipped with an electrode surface cleaning tool that consists of an electrical insulator that does not participate in the behavior of electrons that rotate in the flow of the liquid with the rod-shaped electrode as the rotation axis and affects the measured value of the oxidation-reduction potential. The operation of the above does not affect the measurement value, so that the cleaning of the surface of the rod-shaped electrode and the adhesion of contaminants are prevented, so that no maintenance is required and continuous monitoring measurement can be performed.

  In addition, by rotating the electrode surface cleaning device naturally by the flow force of the liquid during measurement, the rod-shaped electrode outer surface and the inner surface of the through-hole of the electrode surface cleaning device rub against each other, thereby efficiently treating the oxide film on the rod-shaped electrode surface. Thus, the electrochemical reaction activity on the surface of the rod-shaped electrode is increased, and a stable measurement value can be obtained in a short time.

  FIG. 1 is an explanatory view of an oxidation-reduction potential measuring device incorporating a rod-shaped electrode cleaning device according to the present invention. A is an overview of the entire oxidation-reduction potential measuring device, and B is an enlarged view of a rod-shaped electrode cleaning device. , C show the electrode surface cleaning tool in an enlarged manner from the bottom. Here, an example is shown in which the oxidation-reduction potential of the measurement solution flowing in the pipe 10 constituting the flow path is measured. The oxidation-reduction potential measuring device 12 is mainly composed of a rod-like electrode 14 inserted into a measurement solution, an oxidation-reduction potential measuring unit 16 that measures the oxidation-reduction potential through the rod-like electrode 14, and a signal line to the oxidation-reduction measurement unit 16. 18, a measurement display unit 20 that controls the display of the measurement result to the observer and the like. The rod-shaped electrode 14 is made of, for example, platinum or gold. In general, in this type of measuring apparatus, a reference electrode is also provided at the same time. However, in this embodiment, it is not shown because it is built in the oxidation-reduction potential measuring unit 16. In this embodiment, the oxidation-reduction potential measurement unit is installed in the pipe. However, the oxidation-reduction potential measurement unit can be used directly in the measurement solution.

  A rod-shaped electrode cleaning device 30 is incorporated in such a redox potential measuring device 12. The rod-shaped electrode cleaning device 30 includes an electrode surface cleaning device 32 that removes and prevents adhesion of the surface of the rod-shaped electrode 14, and a support 34 that holds the electrode surface cleaning device 32.

  The electrode surface cleaning device 32 has a cylindrical boss portion 38 provided with a through hole 36 into which the rod-shaped electrode 14 is loosely fitted, and four curved structures radially arranged at equal angles on the outer periphery of the boss portion 38. The blade 40 is provided, and the whole is an integrally molded product made of an electrically insulating plastic. By disposing the boss portion 38 of the electrode surface cleaning device 32 so as to surround the rod-shaped electrode 14, the entire electrode surface cleaning device 32 is rotatable about the rod-shaped electrode 14. The length of the boss portion 38 is preferably about 1/3 to 1/2 of the length of the rod electrode 14. Further, the gap G between the outer diameter of the rod-shaped electrode 14 and the through hole 36 is appropriately determined according to the use state and material (size of water flow and frictional force between instruments), and is set to about 1 mm, for example. If the gap is too narrow, the electrode surface cleaning tool 32 is difficult to rotate, and if it is too wide, the rotation becomes unstable.

  The support 34 has a frame-like structure 42 (or a net-like structure) so that the measurement solution can flow without resistance. The upper end of the support 34 is fixed to the lower end of the oxidation-reduction potential measuring unit 16 and is located at the center of the bottom. An upward bar-like protrusion 44 is provided so that the electrode surface cleaning device 32 can be held so as not to drop off. Therefore, the rod-shaped protrusions 44 have the same or smaller diameter as the rod-shaped electrode 14, and both are arranged on the same axis with a slight gap. When the electrode surface cleaning device 32 is made of a material that exerts buoyancy, the electrode surface cleaning device 32 is fitted into the rod-shaped electrode 14 in a natural state, and therefore, in principle, the holder 34 may be omitted. The holder 34 prevents it from falling off.

  The measurement solution flows in the pipe 10. The force of the flow is converted into a rotational force by the blades 40. The electrode surface cleaning device 32 rotates about the rod-shaped electrode 14 by the rotational force, and the inner surface of the through hole of the electrode surface cleaning device 32 rubs against the outer surface of the rod-shaped electrode, thereby cleaning the surface of the rod-shaped electrode (removal of coatings and foreign matters Prevention). FIG. 2 shows an outline of cleaning of the rod-shaped electrode surface by the electrode surface cleaning tool 32 according to the present invention. Due to the rotation of the electrode surface cleaning device 32 due to the flow of the measurement solution, the inner surface of the through hole 36 rotates while rubbing the surface of the rod electrode 14. The electrode surface cleaning tool 32 rotates while moving up and down irregularly by the flow force, and contacts at various points on the surface of the rod-shaped electrode 14 as shown in FIGS. Thereby, the entire surface of the rod-shaped electrode 14 can be cleaned efficiently.

FIG. 3 shows an example in which the electrode surface cleaning tool 32 is attached to the rod-shaped electrode 14 for measuring the oxidation-reduction potential and the oxidation-reduction potential is measured. The oxidation-reduction potential of two types of sodium sulfide (Na ₂ S) solutions (measurement solution 1 having a concentration of 5.8 ppm and measurement solution 2 having a concentration of 9.3 ppm) was measured, and whether or not the electrode surface cleaning device 32 was attached. The relationship of the time required to obtain a stable potential value is shown. When neither the measurement solution 1 nor the measurement solution 2 is attached with the electrode surface cleaning device 32, the response of the redox potential measurement value is slow and very long until reaching a stable value as shown by the long chain lines j and k. It takes time. When the electrode surface cleaning device 32 is attached to each rod electrode 14 inserted in the measurement solutions 1 and 2 at the elapsed time a, the measurement solution 1 is about 30 minutes (time point b) and the measurement solution 2 is about 40 The measured value decreases and reaches a stable state at the minute (time point c). After obtaining stable measurement values for both measurement solutions, the electrode surface cleaning device 32 is removed (at time d for measurement solution 1 and at time g for measurement solution 2), but the measured value rises, but the electrode surface cleaning device 32 is attached again. When the cleaning of the surface of the rod-shaped electrode 14 is started (time e for measurement solution 1, time h for measurement solution 2), it is obtained at time f at measurement solution 1, time i at measurement solution 2, time b and time c. It can be seen that the measured value is similar to the stable value, and that the measured value is reproducible. Incidentally, the measurement accuracy of the rod-shaped electrode 14 used is ± 2 mV. Note that the reason for the increase in the measured value from the time point d to the time point e and from the time point g to the time point h may be that a film is formed on the rod-shaped electrode surface. By using the electrode surface cleaning device 32 continuously, a stable measurement value can be obtained over a long period of time. The measured values obtained in a short time using the electrode surface cleaning device 32 with both measurement solutions are sulfur species S ₂ O ₃ ²⁻ and SO ₃ that are considered to exist in the sodium sulfide (Na ₂ S) liquid. ^{In the} redox reaction between the two, it agrees with the theoretically calculated redox equilibrium potential, and it is confirmed that highly reliable measurement values can be obtained in a short time by using the electrode surface cleaning device 32. did it.

  The present invention can be used in various industrial fields, such as geochemical and biochemical surveys for samples such as natural water having a low chemical buffering property, and long-term environmental monitoring. In the present invention, the shape and number of the blades may be appropriately changed according to the use state. The inner surface of the boss portion can be coated with another material such as glass or ceramic in order to further improve the cleaning effect. In addition, a configuration in which the cylindrical boss portion is made of glass or ceramic, and the blade is made of plastic and fixed is also possible.

Explanatory drawing of the oxidation reduction potential measuring apparatus provided with the electrode surface cleaning instrument which concerns on this invention. The grinding | polishing schematic diagram of the rod-shaped electrode surface by the electrode surface cleaning instrument of this invention. The figure which shows transition of the oxidation-reduction potential measurement data by the presence or absence of an electrode surface cleaning instrument.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Piping 12 Oxidation-reduction potential measuring device 14 Bar-shaped electrode 16 Oxidation-reduction potential measuring unit 18 Signal line 20 Measurement control unit 30 Bar-shaped electrode cleaning device 32 Electrode surface cleaning instrument 34 Support jig 36 Through hole 38 Boss unit 40 Blade 42 Frame shape Structure 44 Rod-shaped projection

Claims (4)

An apparatus for cleaning the surface of a rod-shaped electrode inserted in a flow path using a cleaning instrument that rotates using the flow force of a measurement liquid flowing in the flow path,
An electrode surface that includes a boss portion having a through-hole into which the rod-shaped electrode is loosely fitted, and a plurality of blades disposed around the boss portion, and is rotatable and vertically movable as a whole with the rod-shaped electrode as a supporting shaft. A cleaning tool and a support for holding the electrode surface cleaning tool so that it does not fall off, and the electrode surface cleaning tool rotates in an eccentric state while moving up and down irregularly due to the flow force of the measurement liquid, and passes through The rod-shaped electrode cleaning apparatus is characterized in that the inner surface of the hole is directly rubbed at various locations on the outer surface of the rod-shaped electrode to clean the surface of the rod-shaped electrode.   2. The rod-shaped electrode cleaning apparatus according to claim 1, wherein the electrode surface cleaning device is an integrally molded product of electrically insulating plastic in which a plurality of curved structure blades are arranged at equal angles on the outer periphery of a cylindrical boss portion.   3. The support according to claim 1, wherein the support is a frame-like or net-like structure, and has a rod-like protrusion that can be loosely fitted into the through-hole so that the rotatable electrode surface cleaning device does not fall off. Bar electrode cleaning device. The electrode according to any one of claims 1 to 3, further comprising: a rod-shaped electrode; an oxidation-reduction potential measurement unit that measures the oxidation-reduction potential through the rod-shaped electrode; and a measurement control unit that controls display of the measurement result. An oxidation-reduction potential measuring device incorporating a rod-shaped electrode cleaning device.

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